I really should read the Asia Times more often.

Treat this as a working theory, but an interesting possibility.

Contacts close to the power circles in Pakistan told Asia Times Online that there is a feeling that the US is prepared to take "hurricane" measures to ensure the safety of the country's nuclear arsenal. The thinking goes that by changing horses and supporting Bhutto, the US could exploit the current unrest by dictating new terms to Pakistan in the "war on terror" and coerce it into allowing the US to safeguard its nuclear stockpile.

US Deputy Secretary of State John Negroponte is due to travel to Pakistan this week to meet with senior officials and call for free and fair elections, echoing Bhutto's stance. ....

Indeed, the US belief that it could in some way get its hands on Pakistan's "red" nuclear buttons, by exploiting unrest for which it is partly responsible, sends alarm bells ringing in Islamabad.

Enter, therefore, King Abdullah of Saudi Arabia, whom Musharraf is expected to meet "soon" in Riyadh for what the official Pakistani media describe as "important discussions".

Would Bhutto have called for Musharraf's resignation without the US?

I guess we watch Negroponte and King Abdullah's visits.